Have you considered SEC/GPC?

Try by melt viscosity method

https://books.google.iq/books?isbn=047028997X

Try by melt viscosity method or Rats method

Dear Shaileshkumar Baskaran;

There are multitude methods of determining the different average molecular weights of polymers.

1- Gel Permeation Chromatography (GPC) provides the Mn, Mw, Mz.

2- Ubbelhode viscometer can also give you molecular weight from viscosity of polymer.

3- Light Scattering (It can measure polydispersity).

4- Ebullioscopy (boiling point elevation) and Cryosocopy (freezing point depression).

Best Regards

Thanks to all researchers for the good clarification